The only known German footage of a homicidal gassing can be seen in the documentary Nuremberg: Its Lesson for Today (1948), partially available, among other places, at USHMM's website, 0:44-1:21.
The USHMM description reads:

CU pipes from a German police car bearing a license plate POL-28545 and a German police truck with license POL-51628 (as well as military unit markings: 7 circle-with-flag IX). Apparently metal piping is directed into the brick work of a small brick building, in an area that appears to be a bricked up window or door. Projected against the wall is what appears to be the shadow of a man in uniform. Five emaciated men pass on an open farm cart/wagon to a wooded location; a tall naked emaciated man and two emaciated children (different from those seen first) are led by a man and a woman in white lab coats to the building. Small red cross appears on man's white coat sleeve. The man and woman put blankets around the patients' shoulders as they are led toward the building (and over a child lying on the cart). A uniformed man - probably German - is visible in the background, along the fence, watching the scene. CU car and pipes connecting the car exhaust to the building. [Scene is consistent with descriptions of September 1941 experimental killings by Einsatzgruppe B of patients from a local asylum in the area of Mogilev, Belarus. Corresponding still images were used in evidence at the trial of Albert Widmann.]

The question of what the events on the tape correspond to will be addressed by Hans in parts 3 to 5 of this multi-part article.
In this part we'll take a look at the issue of the provenance of this footage.

Usually it is claimed that the film was found in 1949 in the Berlin apartment of Arthur Nebe, the former commander of Einsatzgruppe B. E.g. Gerald Reitlinger writes (The Final Solution, 2nd edn., 1961, p. 137):

This story von dem Bach-Zelewski’s finds some confirmation in the discovery in 1949 in Nebe’s former Berlin apartment of an amateur film, showing a gas chamber operated by the exhausts of a car and a lorry.

However it had already been used in the above-mentioned documentary, so we know that at least Reitlinger's date is incorrect.
The documentary's director was Stuart Schulberg. How did he acquire the footage? We learn the story from a 2012 article by his daughter Sandra Schulberg, entitled "Filmmakers for the prosecution: the making of Nuremberg: Its Lesson for Today" (pdf):

Belated Find

More than six months had passed since the Nuremberg judgment. Schulberg and Zigman were pushing hard to complete their film, working out of cutting rooms at Berlin’s Tempelhof Studio. In June, they found new, explosive footage. It was turned over to Schulberg by a Dr. Rudolf Goldschmidt, who had acquired the Berlin residence of Artur Nebe, former commander of SS Einsatzgruppen B. In September and October 1941, Nebe’s SS unit had been charged with liquidating the Jews of Mogilev and Minsk, as well as patients from the area’s lunatic asylums. Their efforts were facilitated by Albert Widmann, a chemist affiliated with the Forensics Institute in Berlin, who conducted what are believed to be the Nazis’ first experimental gassing of human beings. This use of an improvised gas chamber was apparently filmed by Nebe himself. Based in part on the success of this experiment, the Nazis later applied this method of asphyxiation on a wider scale, deploying mobile gas vans in the occupied territories. Indescribing the find, Schulberg wrote: “This material is the only known film showing such an atrocity at the very point of being committed. In our opinion, it is a most vital and important contribution to the film evidence of Nazi barbarism.”

One of the footnotes to this paragraph reads:

Memo from Stuart Schulberg to Dr. Goldschmidt, June 18, 1947, acknowledging receipt of the film material shot by Nebe, and describing its content, Schulberg Family Archive.

The memo is also mentioned in the list of documents pertaining to the film's origin at Sandra Schulberg's website dedicated to the film:

The papers of Stuart Schulberg revealed that he added the sound effect of the car’s engine running. That sequence, now with the sound removed, forms part of a special “Deadly Medicine” exhibit at the Holocaust Museum.

The following then applies only to the visual part of the footage.

Before 1933 Dr. Rudolf Goldschmidt was a representative of Metro-Goldwyn-Mayer in Germany, as a "half-Jew" he remained in Berlin during the wartime, apparently in hiding, after the war he became the head of the Film Distribution Agency and then a representative of the Motion Picture Export Association (B.S.Chamberlin, Kultur auf Trümmern. Berliner Berichte der amerikanischen Information Control Section Juli - Dezember 1945, 2010, S.37fn14).

Arthur Nebe's address can be found in Berliner Adreßbuch 1943, Bd.1, S. 2058: it is listed as Hoensbroechstrasse 59. Since 1947 it's Ilsensteinweg 59.

If we then take a look at the International Motion Picture Almanac, 1950, p.697, we see that "Dr. Rudolph Goldschmidt" is listed with the address "Ilsenstein Weg 59".

Sandra Schulberg's information is thus amply confirmed: Dr. Goldschmidt did acquire Nebe's former Berlin residence and thus was in a position to find what lay hidden there.
Since Dr. Goldschmidt was involved in the film business, it is also not surprising that he knew Stuart Schulberg and turned his find over to him.

The provenance of the footage is thus established: it was found in Arthur Nebe's residence not later than in June of 1947.

2 comments:

1. The man and woman in white coats were members of the staff of the Soviet mental hospital at Mogilev from which the victims were taken. That is shown by the hat worn by the woman, which was typical of the dress of Soviet female medical personnel. German accounts of the gassing also refer to the cooperation of the staff of the Mogilev mental hospital in the killing of the patients.

2. The emaciated condition of the victims was a result of their treatment in Soviet mental hospitals and orphanages, where malnutrition was widespread due to the subsistence rations provided to the inmates. In October 1968 I spent a week in one of the Soviet Union's premier hospitals, the Bolnitsa Imeni Botkina in Moscow, so I have personal experience of how little food patients were given, in my case a small bowl of gruel for breakfast, another bowl for lunch, and a bowl of gruel with raisins for dinner. I remember being constantly hungry. No doubt the inmates of Soviet mental hospitals in the 1930s and early 1940s received even less.

Yes, we point out the Soviet personnel later in the series. It is one of the signs of the footage's authenticity.

It is quite probable that the patients were not receiving what we would consider proper rations in the pre-war hospital, but there is no doubt that the German aggression and the occupation made things much worse (even ignoring the murder for a moment).